Since the mid-1960's, the way most deaf and hard-of-hearing people in the United States have telecommunicated is to rely on Public Switched Telephone Network (“PSTN”)-connected text terminals, commonly known as TeleTYpewriters (“TTY's). Typically, the way that a TTY user interacts with a non-TTY user is for the call to be placed via a “relay service.” In this scenario, the relay operator acts as a text-to-speech and speech-to-text translator. The TTY user sends text to the relay operator, the relay operator reads the text to the non-TTY user, the non-TTY user then speaks to the relay operator, who then types the corresponding text to the TTY user. One notable exception to this scenario is that emergency response agents at a Public Safety Answering Point (“PSAP”), a physical location where 911 emergency telephone calls are received and then routed to the proper emergency services, must be able to interact with TTY users directly, without requiring the 9-1-1 calls to be placed via a relay service.
A problem is that the signaling protocol used by TTYs, namely 45.45 baud Baudot, has several limitations, notably a maximum transmission rate of only six characters per second, a very limited character set (for example, there are no lower case letters), and a half-duplex transmit/receive model that requires users to take turns typing to each other. For this reason, many people in the deaf and hard-of-hearing communities prefer the conversational functionality that is supported by browser-equipped Internet-connected Personal Computers (“PCs”). Common examples run the gamut from simple conversational text and Instant Messaging (“IM”) protocols through high-bandwidth video connections that support the transmission and receipt of sign language. Because the browser-based PC interfaces are so much faster and more user-friendly than the TTY interface, IP-access relay services have grown tremendously in popularity, to the point that many states now classify IP relay as a reimbursable service, i.e., a service that is provided without charge to the user, paid for by the same “universal service” fund that covers the expenses of PSTN-based relay. Not surprisingly, many people in the deaf and hard-of-hearing communities have abandoned their TTYs and have adopted IP-based text and video as their primary means of telecommunication.
The migration from TTY devices to IP mechanisms has created a new problem. Public Safety Answering Points (“PSAPs””) rely on “caller ID” information to respond quickly and correctly to incoming calls. Specifically, the ID of an incoming call triggers a rapid automatic response from the PSAP's emergency database. This allows PSAP agents to view critical data immediately, such as the caller's medical history, location, and directions to that location. Caller ID information is provided to PSAPs with calls that are made via PSTN-connected TTYs. Unfortunately, this information is not provided when the originating endpoint is an IP-connected PC. For this reason, emergency response specialists at the PSAP must manually/textually ask the caller to provide the information that would normally be available automatically, thereby delaying the response and making it more likely that the response will be incorrect.
In response to the problem as well as problems associated with non-emergency identification of IP relay service users, the FCC has recently adopted rules “Federal Register/Vol. 73, No. 139/Friday, Jul. 18, 2008/Rules and Regulations”, requiring the assignment of a ten-digit telephone number in the North American Numbering Plan (“NANP”) to every valid user of IP text and video relay. These FCC rules outline the establishment of a central data repository for mapping IP addresses of Internet connected devices to a valid PSTN phone number that has been assigned to a certified user. The rules further specify generally the establishment of a neutral third party entity to construct and manage this repository. Also outlined in the rules is the need for the third party non-government agency to issue ten-digit NANP numbers, either as an authorized telephony carrier or in cooperative partnership with carriers.
Unfortunately, the FCC's explanatory document (http://www.fcc.gov/cgb/consumerfacts/trstendigit.html) provides no engineering guidance about how the FCC's objectives are to be achieved. What they seem to be envisioning is that ten-digit phone numbers can be mapped to specific IP addresses. The problem with this approach is that it does not account for the highly dynamic and transient nature of IP address assignment to networked devices. IP addresses are almost always dynamically assigned to networked devices and can change unpredictably as a device is connected, disconnected, and then reconnected again, to an IP network. Given this situation, there is no reliable and efficient way of tracking a specific user and device in relation to the IP address assigned to that device.
A related problem with the ruling is that there must be a centralized database and mechanism, such that the users of non-telephony Internet communication media can be identified automatically and immediately based on the ten-digit phone number. The assignment of ten-digit phone numbers and the subsequent maintenance of the databases that contain those mappings would probably be the responsibility of the relay services, chiefly because they are the intersection point between the IP network and the PSTN. If IP addresses are to be used as the basis for the mappings, the service provider would need access to an authoritative entity that can be relied upon to provide accurate and timely tracking information of a specific device's IP address changes over time. Because of the way IP networks are engineered, with private LANs and virtual IPs behind NAT (Network Address Translation) boundaries, no such entity exists. Further, it is clear that no such entity could ever be successfully constructed using the networking technologies in common use today.
The shortfall is currently addressed in part by requiring users of IP relay services to enter accurate location information as part of their IP relay session initiation and use. In emergency situations, however, the ability of the contactor to enter accurate location information may be compromised due to physical or emotional condition. Accordingly, there is still a need for a method and system for complying with the FCC rules.